This disclosure generally relates to a pressure control valve. In particular, this disclosure is directed to an electrically operated valve to control the level of vapor pressure in a fuel tank of a vehicle.
It is believed that prior to legislation requiring vehicles to store hydrocarbon vapors that are generated when refueling a vehicle, a simple orifice structure was used to maintain a positive pressure in a fuel tank to retard vapor generation. It is believed that such orifice structures could no longer be used with the advent of requirements controlling on-board refueling. It is believed that, on some vehicles, the orifice structure was simply deleted, and on other vehicles, the orifice structure was replaced with a diaphragm-actuated pressure relief valve. It is believed that these diaphragm-actuated valves suffer from a number of disadvantages including that the calibration (i.e., pressure blow-off level) changes with temperature and age.
It is believed that it is necessary on some vehicles to maintain an elevated pressure in the fuel tank to suppress the rate of fuel vapor generation and to minimize hydrocarbon emissions to the atmosphere. It is believed that under hot ambient temperature conditions or when the fuel is agitated, e.g., when a vehicle is operated on a bumpy road, the amount of fuel vapor generated can exceed the amount of fuel vapor that can be purged by the engine. It is believed that a purge canister can become hydrocarbon saturated if these conditions occur and are maintained for an extended period. It is believed that such a hydrocarbon saturated purge canister is unable to absorb the additional fuel vapors that occur during vehicle refueling, and that hydrocarbon vapors are released into the atmosphere.
It is believed that there is a need to provide a valve that that overcomes the drawbacks of orifice structures and diaphragm-actuated pressure relief valves.
The present invention provides a valve structure that comprises a housing and a valve. The housing includes a first fluid communication passage between a first port and a second port. The valve is movable with respect to the housing between a first configuration, a second configuration, and an intermediate or third configuration between the first and second configurations. The first configuration permits substantially unrestricted fluid flow between the first and second ports. The second configuration substantially prevents fluid flow between the first and second ports. And the intermediate configuration provides restricted fluid flow between the first and second ports. The valve includes a first valve element and a second valve element. The first valve element includes a second fluid communication passage providing the restricted fluid flow between the first and second ports. The second valve element is positional between first and second locations with respect to the first valve element. The first location of the second valve element substantially permits the restricted fluid flow through the second fluid communication passage. And the second location of the second valve substantially prevents the restricted fluid flow through the second fluid communication passage.
The present invention also provides a valve for controlling fuel vapor pressure in a fuel tank. The valve comprises a housing, an electromagnetic actuator, a first body, a second body, a first resilient element, and a second resilient element. The housing includes an inlet port and an outlet port. The electromagnetic actuator includes a stator and an armature. The stator is fixed with respect to the housing, and the armature is displaceable along an axis with respect to the stator. The first body is fixed to the armature and is displaceable along the axis with respect to the housing. The first body includes a conduit, a projection, an end cap, and at least one radial aperture. The conduit extends along the axis between first and second ends. The conduit has an interior volume in fluid communication with the inlet port via the first end. The projection extends radially outward from the first end. The end cap occludes the second end and projects radially outward from the conduit. The at least one radial aperture penetrates the conduit and is located proximate the second end relative to the first end. The second body is displaceable along the axis with respect to the housing and is telescopically disposed with respect to the first body. The second body includes a tube and a flange. The tube is displaceable with respect to the conduit between the end cap and the projection. The flange extends radially outward from the tube and is located proximate the first end of the conduit relative to the second end of the conduit. The first resilient element extends between the end cap and the flange and biases the second body toward the first end of the conduit. The second resilient element extends between the first body and the housing and opposes an actuating force of the electromagnetic actuator. There are a plurality of configurations of the first and second bodies with respect to the housing including a first configuration, a second configuration, and a third configuration. The first configuration permits substantially unrestricted fuel vapor flow from the inlet port to the outlet port. In the first configuration, the flange is spaced from the housing such that fluid communication is permitted between the inlet and outlet ports via a gap between the flange and the housing, and the second body is positioned toward the first end of the conduit such that fluid communication is permitted between the inlet and outlet ports via a combination of the first end of the conduit, the interior volume of the conduit, and the at least one aperture penetrating the conduit. The second configuration substantially prevents fuel vapor flow from the inlet port to the outlet port. In the second configuration, the flange engages the housing such that the gap is closed, and the second body is positioned away from the second end of the conduit such that the tube occludes the at least one aperture. The third configuration provides restricted fuel vapor flow from the inlet port to the outlet port. In the third configuration, the flange engages the housing such that the gap is closed, and the second body is displaced toward the first end of the conduit such that fluid communication is permitted between the inlet and outlet ports via that combination of the first end of the conduit, the interior volume of the conduit, and the at least one aperture penetrating the conduit.